Conclusions
The favorable effect of Aoc and PEG&sub2; linker in reducing the renal uptake provided a new insight into the design of novel dual receptor-targeting radiolabeled peptides.
Methods
The RGD motif {Arg-Gly-Asp-DTyr-Asp} was coupled to [Cys(3,4,10), D-Phe(7), Arg(11)]α-MSH&sub3;₋&sub1;&sub3; via the Aoc or PEG&sub2; linker to generate RGD-Aoc-(Arg(11))CCMSH and RGD-PEG-(Arg(11))CCMSH. The biodistribution
Results
The substitution of Lys linker with Aoc and PEG&sub2; linker significantly reduced the renal uptake of (99m)Tc-RGD-Aoc-(Arg(11))CCMSH and (99m)Tc-RGD-PEG&sub2;-(Arg(11))CCMSH by 58% and 63% at 2h post-injection. The renal uptake of (99m)Tc-RGD-Aoc-(Arg(11))CCMSH and (99m)Tc-RGD-PEG&sub2;-(Arg(11))CCMSH was 27.93 ± 3.98 and 22.01 ± 9.89% ID/g at 2 h post-injection. (99m)Tc-RGD-Aoc-(Arg(11))CCMSH displayed higher tumor uptake than (99m)Tc-RGD-PEG&sub2;-(Arg(11))CCMSH (2.35 ± 0.12 vs. 1.71 ± 0.25% ID/g at 2 h post-injection). The M21 human melanoma lesions could be clearly visualized by SPECT/CT using (99m)Tc-RGD-Aoc-(Arg(11))CCMSH as an imaging probe. Conclusions: The favorable effect of Aoc and PEG&sub2; linker in reducing the renal uptake provided a new insight into the design of novel dual receptor-targeting radiolabeled peptides.